Elaboração e validação de escala diagramática para avaliação da severidade da ferrugem branca do crisântemo

Barbosa, M. A. G.; Michereff, Sami Jorge; Mora-Aguilera, Gustavo

doi:10.1590/s0100-54052006000100008

Cited by 16 publications

(13 citation statements)

References 5 publications

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“…The determination coefficient (R 2 ) of the linear regression equations in comparison with the evaluators' estimates among themselves was lower without using the diagrammatic scale, ranging from 0.61 to 0.91, and 76% of the cases were ≥0.75. In contrast, when using the scale, the evaluations of PPD severity had higher determination coefficients (R 2 ), which varied from 0.83 to 0.95 and were ≥0.75 in 100% of the cases, similarly to what was found in the validation of a diagrammatic scale for other pathosystems (Martins et al, 2004;Barbosa et al, 2006) (Table 2).…”

Section: Resultssupporting

confidence: 60%

Development of a diagrammatic scale for the evaluation of postharvest physiological deterioration in cassava roots

Venturini

Santos

Oliveira

2015

Pesq. agropec. bras.

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-The objective of this work was to develop a scale to assess the severity of postharvest physiological deterioration (PPD) of cassava roots, and to validate this scale for accuracy and reproducibility estimates. A diagrammatic scale (0 to 100%) for the damaged roots was analyzed according to precision, accuracy, and reproducibility. Seven evaluators (four with experience and three without it) quantified the PPD severity, with or without the scale, considering 150 roots with different levels of PPD. Without and with the use of the scale, respectively, the inexperienced evaluators obtained coefficients of determination (R 2 ) from 0.76 to 0.86 and 0.87 to 0.92, and the experienced evaluators obtained R 2 from 0.90 to 0.96 and 0.96 to 0.97. The values of the intercept (a) obtained by both the experienced and inexperienced evaluators who did not use the scale were all significant, while after using the scale, only two evaluators got values that were not significantly different from one. Evaluation reproducibility between the evaluators ranged from 0.61 to 0.91 for the inexperienced ones and from 0.83 to 0.95 for the experienced ones. The proposed diagrammatic scale was considered appropriate to estimate the severity of PPD in cassava roots, and can be used to identify sources of tolerance to postharvest deterioration.Index terms: Manihot esculenta, physiological processes, shelf life, subsistence crop, tolerance. Desenvolvimento de escala diagramática para avaliação da deterioração fisiológica pós-colheita em mandiocaResumo -O objetivo deste trabalho foi desenvolver uma escala para avaliar a severidade da deterioração fisiológica pós-colheita (DFPC) da mandioca, e validar esta escala quanto a estimativas de acurácia e reprodutibilidade. Uma escala diagramática (0 a 100%) referente à área lesionada das raízes foi avaliada de acordo com sua precisão, acurácia e reprodutibilidade. Sete avaliadores (quatro experientes e três inexperientes) quantificaram a severidade da DFPC, com ou sem o uso da escala, tendo-se considerado 150 raízes com diferentes níveis de DFPC. Sem e com o uso da escala, respectivamente, os avaliadores inexperientes obtiveram coeficiente de determinação (R 2 ) de 0,76 a 0,86 e de 0,87 a 0,92, e os avaliadores experientes obtiveram R 2 de 0,90 a 0,96 e de 0,96 a 0,97. Os valores do intercepto (a), obtidos tanto pelos avaliadores experientes como pelos inexperientes, sem uso da escala, foram significativos, enquanto, após o uso da escala, apenas dois avaliadores obtiveram valores que não foram significativamente diferentes de um. A reprodutibilidade das avaliações entre os avaliadores variou de 0,61 a 0,91, para os inexperientes, e de 0,83 a 0,95, para os experientes. A escala diagramática proposta foi considerada adequada para estimar a severidade da DFPC em raízes de mandioca e poderá ser utilizada para identificar fontes de tolerância à deterioração pós-colheita.Termos para indexação: Manihot esculenta, processos fisiológicos, vida de prateleira, culturas de subsistência, tolerância.

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Section: Resultssupporting

confidence: 60%

Development of a diagrammatic scale for the evaluation of postharvest physiological deterioration in cassava roots

Venturini

Santos

Oliveira

2015

Pesq. agropec. bras.

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“…Most of the raters improved estimate precision from the first to second evaluation, which might indicate that as raters get better acquainted with the disease or are trained for disease assessment, estimate accuracy and precision are expected to improve (Michereff et al, 2000;TovarSoto et al, 2002). The precision of the visual estimates of downy mildew severity in melon with the aid of the scale was similar to those observed in recent studies for validation of diagrammatic scales (Barbosa et al, 2006;Godoy et al, 2006), getting fairly close to an ideal agreement, which denotes high precision (Kranz, 1988;Nutter Jr. & Schultz, 1995). Most of the raters reached excellent estimate repeatability when using the scale: in average, 94% of the variation in the first evaluation was explained by the second evaluation.…”

Section: Resultssupporting

confidence: 86%

Diagrammatic scale to assess downy mildew severity in melon

Michereff

Noronha

Lima³

et al. 2009

Hortic. Bras.

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The downy mildew, caused by Pseudoperonospora cubensis, is an important melon disease in Northeast Brazil. Considering the lack of standard methods for its assessment, a diagrammatic scale was developed with 2, 4, 8, 16, 32, 64, 82, and 96% of affected leaf area. The scale was then checked for its accuracy, precision, and reproducibility in estimating downy mildew severity. The diagrammatic scale was validated by eight disease raters; using 50 leaves with different severity levels, previously measured using the software Assess®. Two evaluations were performed on the same set of leaves, but in a different sequence order, by the same raters, within a 15-day interval. The accuracy and precision of each rater was determined by simple linear regression between the actual and the estimated severity. The scale provided good levels of accuracy (means of 87.5%) and excellent levels of precision (means of 94%), with absolute errors concentrated around 10%. Raters showed great repeatability (means of 94%) and reproducibility (>90% in 90.3% of cases) of estimates. Therefore, we could conclude that the diagrammatic scale presented here was suitable for evaluating downy mildew severity in melon.

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“…A validação de uma escala é realizada para aferir se ela está apta a ser utilizada a campo nas mensurações de severidade por pesquisadores e produtores. Neste trabalho, as análises para validação da escala diagramática mostraram que os avaliadores (BARBOSA et al, 2006;GODOY et al, 2006;LENZ et al, 2009), demonstrando a importância dessa ferramenta em estudos de quantificação de doenças. Na primeira etapa da validação da escala diagramática, ou seja, sem a utilização desta, os valores do intercepto de quatro avaliadores (03, 05, 06 e 07) diferiram estatisticamente de zero.…”

Section: Resultsunclassified